Modified series of integrable discrete equations on a square lattice with a non-standard symmetry structure

Abstract: In a paper [TMP, 200:1 (2019), 966--984] by the authors, a series of integrable discrete autonomous equations on a square lattice with a non-standard structure of generalized symmetries is constructed. We build modified series by using discrete non-point transformations. We use both non-invertible linearizable transformations and non-point transformations invertible on solutions of the discrete equation. As a result, we get several series of new examples of discrete equations along with their generalized symmetries and master symmetries. The generalized symmetries constructed give new integrable examples of five- and seven-point differential-difference equations together with their master symmetries. In the case of discrete equations, the method of constructing non-invertible linearizable transformations by using conservation laws is considered, apparently, for the first time.